Induction apparatus for metal coating



Aug. 29, 1950 M. TAMA 2,520,349

INDUCTION APPARATUS FOR METAL COATING Filed Dec. 27, 1948 2 Sheets-Sheet 1 INVENTOR. MAR/0 TAMA ATTORNEY Aug. 29, 1950 A 2,520,349

INDUCTION APPARATUS FOR METAL COATING Filed Dec. 27, 1948 2 Sheets-Sheet 2 IN V EN TOR. MAR/0 TAMAK A 7' TORNE V Patented Aug; 29, 1950 2,520,349 INDUCTION APPARATUS FOR METAL COAT Morrisville, Pa..

Mario Tama,

ING

assiznor to Ajax Engineering Corporation, Trenton, N. J. Application December 27, 1948, Serial No. 67,281 Claims. (Cl. 13-29) The invention relates to an apparatus for metal coating and particularly to a pot or kettle for galvanizing and aluminizing steel and iron articles. Pots used for this purpose are generally made of cast iron; outside heating means such as flues or combustion gases are used to keep the coating metal in the molten state.

The application of the metal coating is effected in the upper section of a molten metal bath, where the coating metal is in its purest state and not contaminated with dross, oxides and other impurities which are formed during the coating process and gradually accumulate on the bottom of the pot; it is, therefore, important to'keep the bottom portion of the metal bath undisturbed.

From the above it is apparent that certain important requirements must be met in the metal coating and particularly in galvanizing and aluminizing practice; these requirements are:

(1) The work must be carried out in the upper zone of the molten metal bath; consequently heat must be applied to the upper portion of the bath or of the pot.

(2) The lower section of the metal bath must be kept in a quiet and undisturbed state so that the contaminations formed during the coating process may freely settle on the bottom of the pot.

(3) The replacement of fresh coating metal must be eifected in the upper portion of the metal bath to prevent contact with the impure bottom portion.

(4) Contamination of the coating metal due to contact with the furnace or pot walls must be avoided.

Various means and methods have been devised to comply with these requirements and their satisfactory fulfillment has become the great problem in metal coating and particularly in galvanizing and aluminizing procedures.

In order to restrict the application of heat to the upper section of the metal bath flues conducting heating gases have been placed in contact and around the upper portion of pots or kettles; devices have been designed to restrict the feed of the fresh metal to the surface of the molten bath and to prevent disturbance of the bottom zone.

These and similar means signify a rather crude and backward approach to the solution of the instant problem; it might well be said that the galvanizing and aluminizing art has not kept in step with the great progress in other metallurgical fields; moreover, the known devices and methods have been developed with the purpose in view to individually comply with each of the above specified requirements.

In contradistinction thereto it is the main object of this invention to provide one common solution of all the problems encountered in galvanizing, aluminizlng and similar metal coating wor It is another object of the invention to charge the fresh metal into the coating pot without disturbance of the bottom portion of the metal bath.

It is a further object of this invention to eliminate contamination of the molten metal bath with the kettle or not walls and to prevent the contact of freshly introduced metal with the impure bottom portion.

It is also an object of this invention to facilitate the charging and heating of the fresh metal supply into the furnace or pot and to accordingly simplify its operation.

A characteristic element of this invention is the supply of the heat to the upper portion of the coating bath in the form of highly heated metal; therefore, the heat which is required for the coating work is generated in the coating metal itself and no foreign heating means which promote oxidation are required.

In compliance with these objects the invention comprises the operative coupling of one or more inductor units customarily used in submerged resistor type induction furnaces with a galvanizing or aluminlzing pot; the inductor unit or units are attached to the galvanizing or aluminizing pot in such a manner as to cooperate with the upper zone of the molten bath.

The provision of replaceable inductor units in low frequency induction furnace is generally known and, for instance, disclosed in applicants U. S. Patent No. 2,423,912. The use of replaceable inclined inductor units in connection with induction, for instance, cylindrical revolving furnaces also belongs to the art; 'in conformity therewith the inductor units are attached to the bottom of the furnaces or to the lowermost part of a side of the cylindrical walls.

The invention provides the operative coupling of one or more inclined and replaceable inductor units with the upper section of a stationary metal coating or galvanizing pot. The molten metal is heated in the inductor unit and propelled by the circulative action towards the upper portion of the coating bath. The thus attained feed of the hot and pure metal into that part of the coating bath exclusively where it is desired is an important element of this invention; the bottom zone of the metal bath remains entirely undia- 3 turbed and the upper portion is accordingly protected against contamination with the impure bottom portion.

It is apparent from the above that the previously recited requirements of galvanizing and aluminizing work are satisfactorily met bythe attachment of one or more inclined inductor units to the upper portion of a stationary metal coating pot.

The invention will now be described more in detail and with references to the accompanying drawing which illustrates a preferred embodiment thereof.

In the drawing Fig. 1 is a partly broken vertical sectional view of a customary longitudinal kettle which is operatively coupled with an inclined inductor unit,

Fig. 2 is a sectional view on line 2 to 2 of Fig. 1 and Fig. 3 is a vertical sectional view similar to Fig. 1 showing the attachment of two inductor units.

The galvanizing pot or kettle i shown in the drawing has a rectangular longitudinal shape; it consists of a steel housing 2 which is provided with a refractory lining 3 enclosing the hearth l2; an inclined opening or passage 5 is provided in the side wall I which passage flares-out into the upper portion of the pot space.

A twin coil inductor unit ll, similar to the one, disclosed in the inventors Reissue Patent No. 22,602 is attached to the wall 1 in such a manner that the inclination of the melting channels 8, 9, I is in alignment with the wall opening or passage and the metal flow only reaches the upper portion of the bath. The refractory lining 4 of the pot has an extension 6 for attachment to the inductor unit.

This replaceable inductor unit consists of a reiractory block l3 which is surrounded by a steel casing It. The unit contains the primary composed in the usual manner of copper coils l5 and iron core IS. The primary threads the secondary melting loop which is formed of a bottom channel 2| and the three melting channels 8, 9, III connecting at their lower ends with the bottom channel and at their upper ends with opening 5 and entering the same preferably at substantially the same level; channel i0 is closed by refractory plugs H, see Fig. 2.

The melting channels 8, 9, ill of the inductor unit extend, as stated above, in the same inclined direction as the wall opening 5; a direct entrance of the hot molten metal is created from the center channel 9 into opening 5 and from there into the upper portion of the galvanizing pot l; the metal returns into the melting channels 8 and III as indicated by the arrows.

The metal, which is constantly heated in the inductor unit, enters into the upper zone of the bath beneath level it; the bottom section therefore remains undisturbed. Contamination of the metal in the upper region of the pot is eliminated; the settling of dross, metal oxides and other impurities on the bottom of the pot is undisturbed. Moreover, a highly accurate maintenance of the temperature in the working zone of the galvanizing pot is obtained due to the exact temperature control in the inductor unit. The center axes 20 of the vertical channels extend towards the open top of the furnace; in this manner the melting channels of the inductor unit can be easily reached and cleaned with cleaning tools.

The work in this apparatus is carried out, as follows:

til

The lining 3 is pre-heated in a suitable manner. Molten coating metal such as molten zinc or aluminum is charged into the hearth I2 of thepot l until the metal overflows into the melting loop of the inductor unit; the current is gradually swltched-on until full power is reached and the hearth is filled to the level i8; the inductor unit and the pot are now in proper working operation. The metal is continuously heated in the melting loop of the inductor unit, transmitted into wall opening 5, from where it flows into the upper working zone of the metal bath. Fresh coating metal may be charged into the hearth l2 in the molten or in the solid state. The articles to be coated are in the usual manner introduced from above.

The inductor unit H is detachable and can be easily replaced, if necessary. The sensitive temperature control of the inductor unit will not only assist in the accuracy of the coating work but also reduce drossing. Since the furnace can be easily operated within exactly controlled small temperature limits wear is greatly reduced.

Various changes may be made of the constructional details disclosed in the foregoing specification without departing from the spirit of the invention.

I claim:

1. An apparatus for metal coating and particularly for galvanizing and aluminizing steel articles comprising a, refractory-lined pot to accommodate a molten bath of the coating metal, an upper uncontaminated zone in said pot housing the articles to be metal coated, at least one inductor unit provided with a primary inductor coil and a secondary melting loop attached to the outside of said pot and connected solely at said upper uncontaminated zone to circulate the metal through the same and a lower sedimentation zone in said pot which is free from said metal circula= tion.

2. An apparatus for metal coating and particularly for galvanizing and aluminizing steel articles comprising a refractorylined pot to ac= commodate a molten bath of the coating metal, an upper uncontaminated zone in said pot housing the articles to be metal coated, at least one inclined inductor unit provided with a primary inductor coil and a secondary melting loop at= tached to the outside of said pot and connected solely at said upper uncontaminated zone to circulate the metal through the same and a lower sedimentation zone in said pot which is free from said metal circulation.

3. In an apparatus for metal coating and particularly for galvanizing and aluminizing steel articles a refractory-lined pot to accommodate a molten bath of the coating metal, an upper uncontaminated zone in said pot which houses the articles to be metal coated, at least one inductor unit provided with a primary inductor coil and a secondary melting loop attached to the outside of said pot, said melting loop being connected solely at said upper uncontaminated zone for a circulation of the metal through the same, a lower sedimentation zone in said pot which is free from said metal circulation the outlets from said secondary melting loop into said pot being located at substantially the same horizontal level.

4. In an apparatus for metal coating and par ticularly for galvanizing and aluminizing steel articles a refractory-lined pot having a top opening to accommodate a. molten bath of the coating metal, an upper uncontaminated zone in said pot which houses the articles to be metal coated,

an inclined inductor unit provided with a primary inductor coil and a secondarymelting loop attached to, the outside of said pot said melting loop being connected solely with said upper uncontaminated zone for a circulation of the molten metal through the same, the axis of said inclined inductor unit extending through said top opening and a lower sedimentation zone in said pot which is free from said metal circulation.

5. In an apparatus for metal coating and par- 10 ticularly for galvanizing and aluminizing steel articles a refractory-lined pot containing an upper uncontaminated zone, the attachment of an inductor unit housing a primary inductor unit and a secondary melting loop connected solely at the upper zone of said pot, which accommodates the articles to be metal coated and a sedimentation zone which is free from metal movement in the lower portion or said pot.

MARIO TAMA.

a REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATE PATENTS Number Name Date 761,920 Schneider June 7, 1904 816,554 Betts Apr. 3, 1906 1,069,923 Crafts Aug. 12, 1913 1,235,628 Wyatt Aug. 7, 1917 1,313,274 De Barros Aug. 19, 1919 2,102,582 Summey Dec. 14, 1937 2,198,304 Cornelius Apr. 23, 1940 2,224,982 Morin Dec. 17, 1940 2,347,298 Tama Apr. 25, 1944 2,427,817 Tama Sept. 23, 1947 

